Furnace stoker



J. s. BENNETT 2,135,697

FURNACE STOKER Filed Oct. 25, 1934 2 Sheets-Sheetl Fig.1.

l1 W |i= 20 W 102 MI 52 5' Will v Jbsebh S NOV. 8, v s N E T FURNACE STOKER 07/ Filed Oct. 2;, 1954 2 Sheets-Sheet? @Wwml Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE Application October 23, 1934; Serial No. 749,539

Claims.

This invention relatesto stoker furnaces, and more particularly to stokers having fluid cooling means associated therewith for preventing cloggingof the tuyere openings by slag and clinker 5 formations. The ash content of certain types of coals it has been found, not only fuses at a comparatively low temperature, but forms an impervious mass when cooled which clogs the air openings of the grates as well as impairs the operation of the stoker as a whole. In many cases it is necessary to extinguish the fire at frequent intervals so that the slag and clinker masses adhering to the grates may be removed.

One object of the present invention is to provide means for preventing such damage to the grates and to insure eflicient burning of all fuels.

Another object is to provide in stoker furnaces of thecharacter set forth means for elevating the Zone of combustion so that incandescentfuel and molten ash will be out of contact with the furnace grates.

A further object is to interpose fluid cooled means between the grates and the incandescent portion of the fuel bed which acts as a screen for cooling any slag flowing through the fuel mass, before-it comes in contact with the grates.

Another object is to provide over the tuyere rows in an underfeed stoker a series of fluid conducting tubes which raises the zone of combusz-ldtion above the tuyeres and chills any slag or clinker formations before they come in contact with the tuyeres, thus minimizing the adherence thereto of such slag or clinker formations.

A still further object is to provide in an under- -.feed stoker a plurality of fluid conducting tubes over the tuyere rows thereof, and also over the extension grates to prevent the adherence of clinkers to the various grates of the stoker, and to insure efficient combustion of all types of fuel thereon.

A further object is to provide an improved furnace tuyre having recesses provided therein. for receiving a series of fluid conducting tubes.

Other and further objects will become apparent as the description of the invention progresses.

Of the drawings:

Fig. 1 is a longitudinal sectional view taken through a stoker furnace showing fluid conducting tubes arranged in cooling relation with the tuyeres, dead plates and ash pocket walls.

Fig. 2 is a plan view of the stoker shown in Fig. 1 with parts broken away to show the arrangement-of certain of the tubes and headers of the 55. fluid cooling system associated therewith.

Fig. 3-is a sectional view taken substantially along line 33 of Fig. 1.

Fig. 4 is a modification of the structure shown in Fig. 3 showing the tubes resting upon the upper surfaceof the tuyre blocks.

Fig. 5 is a further modification of the structure shown in Fig. 3 showing the tubes arranged in spaced relation with respect to the top of the tuyere blocks.

Fig. 6 is a plan View of one of the tuyere blocks provided on the stoker.

Fig. 'l is a sectional side view of the tuyre block shown in Fig. 6.

Referring to the drawings, the numeral l designatesa furnace having provided therein an underfeed stoker 2, comprising alternately disposed retorts 3 and tuyere rows 4. Fuel is fed into the retorts 3 from hoppers 5 by any suitable feeding mechanism 6." Fuel entering the retorts 3 is underfedover the length thereof by a series of pushers 8 to an ash pocket 53 disposed at the rearwardly disposed end of the stoker. Draft air is supplied to the furnace from a plenum chamber 44 disposed beneath the stoker 2. Plenum chamber 44 may be connected to any source of air supply by means of a communicating passage-47. The side walls of the furnace adjacent the stoker 2 have each provided therein a fluid cooled panel l8 comprising front and rear headers l9 and'20 respectively, connected by a series of fluid conducting tubes 2!. A downcomer 22 connects header 20 with the boiler it, while header I!) is connected to the boiler by a riser 23. A series of fluid conducting tubes 25 is mounted on the tuyere blocks of each of the tuyere rows The lower ends of tubes 25 are bent downwardly over the rear end of the stoker and the substantially verticalextensions 54' thereof form a portion of the front wall 54 of the ash pocket 53. The lower ends of tubes 25 then extend forwardly and terminate in a header 55 mounted in any suitable manner beneath the stoker. I The tubes 25 are connected at their upper ends to header 26, wlL'ch in turn may be connected to the boiler l6 by any suitable riser connection 26 A second series of tubes 56 extend rearwardly from a header 5! suitably mounted beneath the stoker, and the substantially horizontal portions thereof are mounted in close juxtaposition with the lower surfaces of the dead plates 58 provided at the lower ends of the retorts of the stoker. The-tubes 56 then extend downwardly and occupy the spaces between the vertically disposed portions 54 of tubes 25 and formtherewiththe exposed portion of the front Wall..54'-'of the ash-pocket.- The lower ends of header 55.

tubes 56 also extend forwardly and terminate in system the header 5! connected to the forwardly disposed ends of tubes 56 may be elevated so as to assume a position in alinement with or slightly above the horizontally disposed portions of said tubes.

Under certain conditions it may be desirable to partially imbed the tubes 25 in the tuyres 4, as indicated in Fig. 3. To this end the nose portion of each tuyre block 4 is provided with a series of depressions 67, which in assembly receive the tubes 25. 'Iuyeres blocks 4 are provided with the usual projections or ribs 68 defining'passages for draft air. contact with the tuyre blocks, as illustrated in Fig. 3, the blocks are effectively cooled and thus capable of withstanding the severe conditions of furnace operation. The draft air flowing through the tuyre blocks also produces a cooling effect thereon. However, under certain conditions, it has been found desirable to simply rest the tubes 25 upon the upper surfaces of the tuyres as shown in Fig. 4. It has also been found desirable in certain installations to space the tubes 25 from the tuyere blocks 4, as shown in Fig. 5. Whether the tubes are to be placed in intimate contact with the tuyere blocks as shown in Fig. 3, or

arranged in the manner shown in Figs. 4 and 5, depends upon the conditions of operation of the furnace and upon the types of fuel to be burned therein. The tubes 25 arranged in the manner shown in Figs. 3, 4 and 5 act as a cooling screen and chill any molten ash flowing toward the tuyeres or extension grates, thus causing the same to partially solidify before coming in contact with the tuyres or grates. The slag or clinker thus chilled will not adhere to the tuyere blocks, and accordingly will be carried down the fuel bed by the general movement of the fuel to the ash pit and dumped therein.

The various constructions herein shown and described not only lower the maintenance cost of stokers, but permit furnaces to operate for long periods of time without interruption. These constructions are especially desirable when the fuels burned are of the type wherein the ash content thereof fuses at low temperatures. This molten ash has a tendency to clog the tuyre openings, and thus prevents the proper amount of air from entering the fuel bed. This also causes considerable damage to the grates with the result that the maintenance cost is not only high, but a considerable loss' is experienced in taking the boilers off the line to make the necessary repairs. The various constructions herein shown'have largely eliminated these undesirable conditions and have therefore is not to be limited to the embodiments Header 51 may also be connected to When the tubes are seated in intimate herein shown since it may be embodied in other forms, all coming within the scope of claims which follow.

What is claimed is:

1. In an underfeed stoker, comprising in combination, alternately disposed tuyere rows and retorts, dead plates disposed near one end of said stoker, a series of fluid conducting tubes mounted over each of said tuyre rows forming a screen for chilling any molten ash passing through the fuel bed toward said tuyres, and a second series of tubes disposed in cooling relation to said dead plates.

2. In an underfeed stoker, comprising in combination, alternately disposed tuyre rows and retorts, an ash pocket disposed at one end of said stoker having a, front wall, dead plates disposed at the bottom of said retorts, a series of fluid conducting tubes mounted over each of said tuyre rows forming a screen for chilling any molten ash passing through the fuel bed toward said tuyres, said tubes extending downwardly and forming a portion of the front wall of said ash pocket and terminating in a header, a second series of tubes disposed beneath said dead plates and in cooling relation therewith, said last mentioned tubes also extending downwardly over the said front wall and in the same plane with said first mentioned tubes and terminating in said header, a boiler, means connecting said tubes and header to said boiler, and a booster pump for feeding fluid under pressure from said boiler to said header.

3. In an underfeed stoker, comprising in combination alternately disposed retorts and tuyre rows, dead plates disposed at the lower end of said retorts, an ash pocket disposed at one end of said stoker having a front wall, a series of fluid conducting tubes mounted over each of said tuyre rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, a second series of tubes disposed beneath said dead plates in cooling relation therewith, and headers connected to the terminal ends of said tubes.

4. In an underfeed stoker, comprising in combination alternately disposed tuyre rows and retorts, an ash pocket disposed at one end of said stoker having a front wall, dead plates disposed at the bottoms of said retorts, a series of fluid conducting tubes mounted over each of said tuyre rows forming a screen for chilling any molten ash passing through the fuel toward said tuyres, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, a second series of tubes disposed beneath said dead plates and in cooling relation therewith, said last mentioned tubes also extending downwardly over said front wall and lying in the same plane with said first mentioned tubes, and headers for the terminal ends of said tubes.

5. In an underfeed stoker, comprising in combination alternately disposed tuyre rows and retorts, an ash pocket disposed at one end of said stoker having a front wall, dead plates disposed at the bottom of said retorts, a series of fluid conducting tubes mounted over each of said tuyere rows forming a screen for chilling any molten ash passing through the fuel toward said tuyres, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, 2. second series of tubes disposed beneath said dead plates and in cooling relation therewith, said last mentioned tubes also extending downwardly over said front wall and lying in the same plane with said first mentioned tubes, a boiler, and means connecting said tubes to said boiler.

6. In an underfeed stoker, comprising alternately disposed retorts and tuyere rows, fuel supporting means disposed at the lower ends of said retorts and lying between said tuyere rows, one or more fluid conducting tubes mounted in cooling relation with the tuyeres of each of said rows, and one or more fluid conducting tubes disposed in cooling relation with said fuel supporting means.

7. In an underfeed stoker, comprising alternately disposed retorts and tuyre rows, of dead plates disposed near one end of said stoker, one or more fluid conducting tubes mounted in cooling relation with the tuyres of each of said rows, and one or more fluid conducting tubes disposed in cooling relation with said dead plates.

8. In an underfeed stoker, comprising alternately disposed retorts and tuyere rows, of fuel supporting means disposed at the lower ends of said retorts and lying between said tuyre rows, an ash pocket disposed at one end of said stoken having a front wall, one or more fluid con-ducting tubes mounted in cooling relation with the tuyres of each of said rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, one or more fluid conducting tubes disposed in cooling relation with said fuel supporting means, and means for supplying fluid to said tubes.

9. In an underfeed stoker, comprising in combination alternately dispose-d retorts and tuyere rows, dead plates disposed at the lower end of said retorts, an ash pocket disposed at one end of said stoker having a front wall, one or more fluid conducting tubes mounted in cooling relation with the tuyres of each of said rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, one or more fluid conducting tubes disposed in cooling relation with said dead plates, and means for supplying fluid to all of said tubes.

10. In an underfeed stoker, comprising alternately disposed retorts and tuyere rows, of fuel supporting means disposed at the lower ends of said retorts and lying between said tuyre rows, an ash pocket disposed at one end of said stoker having a front wall, one or more fluid conducting tubes mounted in cooling relation with the tuyeres of each of said rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, one or more fluid conducting tubes disposed in cooling relation with said fuel supporting means, a boiler, and means operatively connecting said tubes to said boiler.

11. In an underfeed stoker, comprising in combination alternately disposed retorts and tuyere rows, dead plates disposed at the lower end of said retorts, an ash pocket disposed at one end of said stoker having a front wall, one or more fluid conducting tubes mounted in cooling relation with the tuyres of each of said rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, one or more fluid conducting tubes disposed in cooling relation with said dead plates, a boiler, and means operatively connecting said tubes to said boiler.

12'. In an underfeed stoker, comprising alternately disposed retorts and tuyere rows, of fuel supporting means disposed at the lower ends of said retorts and lying between said tuyere rows, an ash pocket disposed at one end of said stoker having a front wall, one or more fluid conducting tubes mounted in cooling relation with the tuyeres of each of said rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, one or more fluid conducting tubes disposed in cooling relation with said fuel supporting means, a boiler, means operatively connecting said tubes to said boiler, and a booster pump for feeding fluid under pressure from said boiler to said tubes.

13. In an underfeed stoker, comprising in combination alternately disposed retorts and tuyere rows, dead plates disposed at the lower end of said retorts, an ash pocket disposed at one end of said stoker having a front wall, one or more fluid conducting tubes mounted in cooling relation with the tuyeres of each of said rows, said tubes extending downwardly and forming a portion of the front wall of said ash pocket, one or more fluid conducting tubes disposed in cooling relation with said dead plates, a boiler, means operatively connecting said tubes to said boiler, and a booster pump for feeding fluid under pressure from said boiler to said tubes.

14. An underfeed stoker, comprising alternately disposed tuyere rows and retorts, fuel supporting means disposed at the lower ends of said retorts and lying between said tuyere rows, one or more fluid conducting tubes mounted above said tuyres and in spaced relation therewith, and one or more fluid conducting tubes disposed in cooling relation with said fuel supportmg means.

15. In a. furnace, the combination of a stoker, comprising alternately disposed retorts and tuyre rows, substantially horizontally disposed fuel supporting means provided at the lower end of each of said retorts, means comprising one or more tubes disposed longitudinally of and V in cooling relation with said fuel supporting means, headers connecting the opposite ends of said tubes, means comprising one or more tubes extending from one of said headers and disposed in cooling relation with said tuyeres, and means for supplying fluid to one of said headers.

JOSEPH S. BENNETT. 

